Add social icon for Archive of Our Own

[geeqla]

What does this PR change? What problem does it solve?

• Add social icon for Archive of Our Own
• Raw SVG source: https://iconduck.com/icons/302015/brand-ao3 (scroll down to preview small variant)
• This is adaptation of the original logo as it is quite difficult to resize

Was the change discussed in an issue or in the Discussions before?

Closes #1072 (FYI: @abovewave)

PR Checklist

• This change adds/updates translations and I have used the template present here.
• I have enabled maintainer edits for this PR.
• I have verified that the code works as described/as intended.
• This change adds a Social Icon which has a permissive license to use it.
• This change does not include any CDN resources/links.
• This change does not include any unrelated scripts such as bash and python scripts.
• This change updates the overridden internal templates from HUGO's repository.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud